From: Ulrich Drepper <drepper@redhat.com>
Date: Sun, 26 Jul 2009 19:55:03 +0000 (-0700)
Subject: Compatibility of signalfd/eventfd with older kernels.
X-Git-Tag: fedora/glibc-2.10.90-9~1^2~4
X-Git-Url: http://repo.or.cz/w/glibc.git?a=commitdiff_plain;h=aa7492d2

Compatibility of signalfd/eventfd with older kernels.
---

diff --git a/sysdeps/unix/sysv/linux/eventfd.c b/sysdeps/unix/sysv/linux/eventfd.c
index 4cd5579..7f69ecd 100644
--- a/sysdeps/unix/sysv/linux/eventfd.c
+++ b/sysdeps/unix/sysv/linux/eventfd.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -19,14 +19,21 @@
 #include <errno.h>
 #include <sys/eventfd.h>
 #include <sysdep.h>
+#include <kernel-features.h>
 
 
 int
 eventfd (int count, int flags)
 {
 #ifdef __NR_eventfd2
-  return INLINE_SYSCALL (eventfd2, 2, count, flags);
-#else
+  int res = INLINE_SYSCALL (eventfd2, 2, count, flags);
+# ifndef __ASSUME_EVENTFD2
+  if (res != -1 || errno != ENOSYS)
+# endif
+    return res;
+#endif
+
+#ifndef __ASSUME_EVENTFD2
   /* The old system call has no flag parameter which is bad.  So we have
      to wait until we have to support to pass additional values to the
      kernel (sys_indirect) before implementing setting flags like
@@ -43,5 +50,7 @@ eventfd (int count, int flags)
   __set_errno (ENOSYS);
   return -1;
 # endif
+#elif !defined __NR_eventfd2
+# error "__ASSUME_EVENTFD2 defined but not __NR_eventfd2"
 #endif
 }
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 4562515..ff065ef 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -516,6 +516,8 @@
 # define __ASSUME_SOCK_CLOEXEC	1
 # define __ASSUME_IN_NONBLOCK	1
 # define __ASSUME_PIPE2		1
+# define __ASSUME_EVENTFD2	1
+# define __ASSUME_SIGNALFD4	1
 #endif
 
 /* Support for the accept4 syscall was added in 2.6.28.  */
diff --git a/sysdeps/unix/sysv/linux/signalfd.c b/sysdeps/unix/sysv/linux/signalfd.c
index 9898f29..c2d974a 100644
--- a/sysdeps/unix/sysv/linux/signalfd.c
+++ b/sysdeps/unix/sysv/linux/signalfd.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2007, 2008 Free Software Foundation, Inc.
+/* Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -20,14 +20,21 @@
 #include <signal.h>
 #include <sys/signalfd.h>
 #include <sysdep.h>
+#include <kernel-features.h>
 
 
 int
 signalfd (int fd, const sigset_t *mask, int flags)
 {
 #ifdef __NR_signalfd4
-  return INLINE_SYSCALL (signalfd4, 4, fd, mask, _NSIG / 8, flags);
-#else
+  int res = INLINE_SYSCALL (signalfd4, 4, fd, mask, _NSIG / 8, flags);
+# ifndef __ASSUME_SIGNALFD4
+  if (res != -1 || errno != ENOSYS)
+# endif
+    return res;
+#endif
+
+#ifndef __ASSUME_SIGNALFD4
   /* The old system call has no flag parameter which is bad.  So we have
      to wait until we have to support to pass additional values to the
      kernel (sys_indirect) before implementing setting flags like
@@ -44,5 +51,7 @@ signalfd (int fd, const sigset_t *mask, int flags)
   __set_errno (ENOSYS);
   return -1;
 # endif
+#elif !defined __NR_signalfd4
+# error "__ASSUME_SIGNALFD4 defined but not __NR_signalfd4"
 #endif
 }